<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <p style="float:left;width :100px;background-color: coral;margin: 0 auto">这个是第1列，</p>

    <p style="float:left;width :400px;background-color: chartreuse;margin: 0 auto">这个是第2列，</p>

    <p style="background-color: cyan;clear: both;width: 200px;margin: 0 auto">这个是列的下面。</p>
    <div style="width: 50px;height: 50px;background-color: #9a9a9a;font-size: 5px;text-align: center;line-height: 50px;
    position: fixed;
    bottom: 10px;
    right: 0">
        返回首页
    </div>
</body>
</html>